Numerous surgical devices are known which utilize laser light as the primary form of energy conveyed by an elongate optic fiber and delivered it at selected locations for ablation or vaporization of tissue. Such devices can generally be divided into two principal categories: first, devices which have an end of the optic fiber itself shaped to emit laser energy in focussed form, e.g., for performing surgical incisions; and, second, devices which include in addition to the optic fiber a tip element which is heated by the laser energy. Such tip elements typically are formed of a ceramic material such as YAG, sapphire or silica, which materials are generally different from the material of the optic fiber. Both types of devices offer advantages and are deemed suitable for specific surgical applications, but both also pose certain problems in their manufacture and subsequent use. Laser surgical devices of these and other types are problems in their manufacture and subsequent use. Laser surgical devices of these and other types are becoming commonly available tools for a variety of surgical operations.
For use with each of these available tools, there are a variety of laser light energy sources capable of controllably delivering continuous or pulsed laser energy fluxes in selected wavebands, ranging from X-rays to infrared. Different advantages are realized by proper selection of the laser energy wavelengths and laser energy delivering tip designs. Copending applications U.S. Ser. Nos. 07/723,984; 07/723,987; 07/724,019; and 07/812,449 teach a variety of tip element forms, structures and improvements, each particularly suited to specific surgical applications.
A single optic fiber is often employed to delivery laser light energy emitted directly from a distal end contacted to tissue to perform incisions, coagulate blood, and/or cauterize severed blood vessels. Such an optic fiber end often degenerates and becomes structurally weak. This may be due to thermal cycling at very high and relatively low local temperatures in the course of repeated contacts with friable tissues.
If the optic fiber is connected to a separate tip element to avoid this, the material of the tip element must be such as to transmit the laser light energy very efficiently to the tissue. Also, Fresnel losses may occur in the interface between the optic fiber and the tip element where optic energy is transmitted between them. Copending applications U.S. Ser. Nos. 07/724,019 and 07/944,384 teach a simple solution to this problem. If the tip element material has a relatively low operating temperature, the same kind of physical degradation can occur as with a directly applied optic fiber end.
Furthermore, in the manner disclosed in the above-cited copending applications, e.g., U.S. Ser. No. 07/723,984, the tip element must be shaped not only to efficiently receive laser light energy from the optic fiber energy delivering end but also to accommodate to and permit certain types of surgical procedures. Such shaping of the energy delivering tip element, considering the materials involved, can be quite expensive even if economies of scale are realized in producing large numbers of such elements.
There is, therefore, an existing need for a way to deliver through a single optic fiber optic energy, e.g. from a laser source, in any of a variety of wavebands, precisely and repeatedly, over prolonged use at high efficiency. The present invention is intended to meet this need.